This type of reading apparatus, generally, employs a mode for reading a document placed at a predetermined distance, and in particular a mode for reading, from above, a document placed face up. Certain improvements are desired of such an image reading apparatus. For example, a satisfactory result cannot be obtained if an obstacle enters a space between a document and an image reader for reading the document during a reading operation.
To cope with such a situation, some apparatus known in the art read a document and display its image on a display device. In this case, if an obstacle enters the space between the document and the image reader, the obstacle is displayed along with the document image on the display device. Upon noting the obstacle, the user carries out a reading operation all over again, However, it is not desirable for the user to have to watch the display device carefully during a reading operation.
A different problem arises when a reading area is input to the apparatus for reading only a selected portion of a document. Regarding this area designation, there is a type of apparatus which reads a document and displays its image on a display device for allowing the user to designate a desired area on the display device. In another type of apparatus, a document is placed on a pressure sensitive board for the user to designate a desired area by pressing the document with a pen or the like. A further apparatus is known from the Japanese patent application laid open under No. 63-232568, in which positions of a document read are monitored by light beams or spot light during a reading operation, and the user turns the scanning operation on and off while watching a monitor screen for reading only a desired area of the document. It is also possible to designate a desired area of a document by marking it with a marker pen.
The apparauts that allows the user to designate an area of a document on a display device is complicated and expensive since the display device is required. With this type of apparatus, an area cannot be designated prior to a reading operation. The apparatus including a pressure sensitive board for designating an area on a document surface does not allow the designation on a thick document. The apparatus in which a scanning operation is turned on and off for reading a selected area of a document is difficult to operate and tends to invite errors. Designation of an area with a marker pen has the disadvantage of marring the document.
One of the aspects currently desired is that confirmation is made of an area of a document to be read when reading the document. To meet this demand, certain apparatus have a document table defining a reading range of a document, and others indicate a reading range by means of scales provided on a document table. A further apparatus is known from the Japanese patent application laid open under No. 62-276958, in which spot or line light is movable with a scanning operation by a reading sensor to illuminate a position of the document currently read.
The apparatus disclosed in the above publication does not show an entire reading range at a time, and is inconvenient for positioning of a document prior to a reading operation. The other apparatus have the disadvantage of failing to show clearly which part of a document is read if the document is larger than the document table. The part of a document is not clearly recognizable even when the document is small.